en Original Research: Clinical Science Original Research: Clinical Science This study sought to compare the clinical features and outcome of a first acute myocardial infarction (AMI) with onset of symptoms during or within 30 minutes of exercise, at rest and in bed. Information collected using a standard questionnaire was used to relate activity at the onset of symptoms and in-hospital outcome in 500 consecutive patients admitted to our heart center with a first AMI between 2000-2002. Patients with exercise-related onset were more likely to be younger and male. Those with onset in bed were more likely to be older and have a history of stable or unstable angina. By way of comparison between patients whose symptoms began at rest and exercise, those with exercise-related onset had lower in-hospital mortality after adjusting for age and gender [odd's ratio (OR) 0.53, 95% confidence interval (CI) 0.39-0.93 (p= 0.03)]. Compared with patients whose symptoms began at rest, patients with onset in bed had a higher mortality rate [OR 1.42,95% CI 1.03 -1.98 (p= 0.028)]. The incidence of moderate or severe left ventricular dysfunction was also lower for exercise -related onset [OR 0.79,95% CI 0.6-1.01 (p= 0.32-but not statistically significant)] and higher when onset was in bed [OR 1.5, 95% CI 1.2-1.77 (p=0.039)]. There is an association between activity at onset and outcome of AMI. Differences in pathophysiology or in the population at risk could explain this observation. Activity, Acute Myocardial Infarction, Outcome. 293 296 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-68&slc_lang=en&sid=1 JAHANBAKHSH SAMADIKHAH 20031947532846003477 20031947532846003477 No From the Shaheed Madani Heart Hospital, Tabriz University of Medical Sciences, Tabriz, Iran. S. HADI HAKIM 20031947532846003478 20031947532846003478 No AZIN ALIZADEH ASL 20031947532846003479 20031947532846003479 No RASOUL AZARFARIN azarfarinr@yahoo.com 20031947532846003480 20031947532846003480 Yes